Internal combustion engines such as diesel engines, gasoline engines, and gaseous fuel-powered engines use injectors to introduce fuel into the combustion chambers of the engine. As the fuel is pressurized, directed through portions of the engine to individual injectors, and returned from the injectors, the fuel absorbs heat from its surroundings and from the work exerted on the fuel. As the fuel is heated, properties of the fuel affecting injection characteristics change. In addition, because fuel heating throughout the engine can vary during operation of the engine, the fuel temperature and, thus, the injection characteristics at one injector may be different from the fuel temperature and injection characteristics at another injector. If these varying temperature and injection characteristics are not accounted for during operation of the engine, the injection of fuel into the engine and subsequent operation of the engine may be unpredictable.
In order to account for these fuel temperature and injection characteristic changes, engine manufacturers have attempted to estimate the fuel temperature at each injector. One such example is disclosed in U.S. Pat. No. 5,865,158 (the '158 patent) issued to Cleveland et al. on Feb. 2, 1999. The '158 patent describes a method and system for controlling the injection of fuel across a plurality of fuel injectors coupled together along a fuel rail in an internal combustion engine. The method includes producing a reference fuel delivery control signal for each fuel injector as a function of a desired fuel mass to be injected. The method further includes adjusting the pulse width of each fuel delivery control signal as a function of the fuel temperature proximate each of the fuel injectors. The temperature of the fuel proximate each injector is ascertained by first measuring the temperature of the fuel near the inlet of the fuel rail. This measured temperature is then offset based on the location of the fuel injector along the rail to determine the temperature of the fuel proximate each injector.
Although the method and system of the '158 patent may estimate the fuel temperature at each injector and control operation of the injectors in response thereto, it may lack accuracy. In particular, the 158 system does not take into account fuel that is directed to other fuel-powered engine accessories or the effect their operation may have on fuel temperature. In addition, the 158 patent does not take into account the current steady-state or transient operation of the engine when determining fuel temperature.
The system and method of the present disclosure solves one or more of the problems set forth above.